results from the halogas surveyresults from the halogas survey: hi observations of ngc 5055 maria...

Results from the HALOGAS Survey: HI Observations of NGC 5055

Maria PattersonTully-Fisher at 35, Global Properties of HI in Galaxies, Green Bank, WV

2 April 2012

George Heald (PI)

Gyula Jozsa

Tom Oosterloo

Paolo Serra

Renzo Sancisi

Filippo Fraternali

Erwin de Blok

Gianfranco Gentile

Rich Rand

Laura Zschaechner

Maria Patterson

Rene Walterbos

Cat Wu

Bjoern Adebahr

Ralf-Juergen Dettmar

Eva Juette

Peter Kamphuis

Bob Benjamin

ASTRON

ASTRON

ASTRON

ASTRON

Osservatorio Astronomico di Bologna

Bologna University

University of Cape Town / ASTRON

Ghent University

University of New Mexico

University of New Mexico

New Mexico State University



Ruhr-Universitat Bochum




University of Wisconsin- Whitewater

HALOGAS Survey Team

2010- 1st meeting, Dwingeloo, Netherlands

2011- 3rd meeting, Bochum, Germany

http://www.astron.nl/halogas/http://www.astron.nl/halogas/

Hydrogen Accretion in LOcal GAlaxieS Survey

20 spiral galaxies (+ NGC 891 (Oosterloo+ '07), NGC 2403 (Fraternali+ '02))

120 hrs for each galaxy

5 times deeper than THINGS

Sensitivity of 3σ at ~1 x 1019 cm-2

The HALOGAS Survey is a deep HI survey with the Westerbork Synthesis Radio Telescope of a sample of neutrally selected nearby spiral galaxies with the goal of detecting faint gas and characterizing accretion.

Neutral selection criteria: Barred and unbarred, Sa-Sd from Tully (1988) catalog

Inclinations: moderately-inclined (50-75°) and edge-on (> 85° )

Declination > +25° (synthesized beamsize < 30“)

dTF88 < 11 Mpc (15“ = 0.7 kpc at 10 Mpc )

D25 > 3' (well-resolved)

Vsys > 100 km/s (avoid MW confusion)

Maria Patterson, HALOGAS Tully-Fisher at 35, 2Apr2012

HALOGAS survey sensitivity

NGC 925 Heald+ (2011 pilot paper)

HALOGAS:

5σ column density limit of

~2.0 x 1019 cm-2

THINGS:

5σ column density limit of

~1 x 1020 cm-2

The HALOGAS data are sensitive to ~1 x 105 M⊙ clouds, at 3σ level for a typical line width of 16 km/s at 10 Mpc.


Goal: Establish the importance of the role of accretion in galaxies

Accretion is key to... Maintaining a ~constant SFR

Metallicity evolution in ISM

Continuing buildup of galaxies- connection to warps and lopsidedness

How many galaxies show evidence for accreting gas?

How much accreting gas is there?

Estimated 1-2 solar masses/yr (Sancisi+ 2008)

How often can 'halo' gas be associated with

infall from the IGM?

minor mergers with smaller satellite galaxies?

returning galactic fountain gas?


10 k

pc

10 k

pc

NGCNGC 891 891

If we look deep enough, how many spiral galaxies look like this?

Fraternali+ (2002)

HVC analogbeard

lagging halo

radial flow

NGC 891:30% (~1.2 x 109 solar masses) of the gas in extraplanar halo component

NGC 2403:10% (~3 x 108 solar masses) of the gas in extraplanar halo component (+ radial flow in halo)

Oosterlo

o+

(2007)

halo

filament

CRClag

NGC 891


Approach Develop a tilted-ring model for each galaxy

Identify discrete clouds and streams to build an 'accretion catalog'

Mass, size, distance and kinematics relative to disk

Cross identify with optical and UV features

Identify galaxies with thick disks / 'halos' for occurence statistics

Radial extent, vertical scaleheight, kinematics

Compare gas properties with galaxy properties on individual basis

Complementary observing campaigns

Compare gas properties with galaxies properties across sample

StatusAll HI observations finished.

Modeling complete / near complete for many targets.

Individual galaxy analysis papers in prep.

Beginning preliminary analysis of sample statistics.

See survey website: http://www.astron.nl/halogas/http://www.astron.nl/halogas/


The HALOGAS data reveal a range of HI features...NGC 1003

Allan/Heald+, in prep

HVC analogs

UGC 4278

Serra+, in prep

Zschaechner+, 2011

NGC 4244

Lag, but no 'halo'

NGC 3198

Gentile+, in prep

Discrete clouds

NGC 3198800

700

600

500 10 kpc

Beard gas


Discrete cloud

NGC 4565

Zschaechner+, in prep

Companion

Image credit: R Jay GaBany

SAbc

Moderately-inclined (55º)

d = 8.5 Mpc

D25=13'=32.5 kpc

SFR= 2.1 solar masses/ yr

THINGS

Battaglia+ 2006

NGC 5055 (M63) previous HI data


Large HI disk

~3.5 x D25

Large HI warp

NGC 5055: HALOGASBattaglia+ 2006 Total HI mass of galaxy:

~ 8.5 x 109 solar masses

HALOGAS


13 kpc ~2.7×107 M☉

14.5 kpc~9.4×106 M☉

700

600

500

400

300

Contours: 2.7 x 2n mJy/beam (3σ x 2n )(1.0 x 1019 x 2n cm-2)

Contours: 270:780, +30 km/s

NGC 5055 moment mapsUGC 8313


companion is separated in velocity, but may be a

connection through the south

?

Tilted-Ring ModelingGroningen Image Processing System (GIPSY) (van der Hulst+ 1992)

GALMOD (and HALOGALMODZ) (Fraternali, Heald)

Tilted Ring Fitting Code (TiRiFiC) (Jozsa et al., 2007)


Contours: 2.7 x 2n mJy/beam Contours:270:780, +30 km/s

Position velocity plots: anomalous gas

major axis


Lagging halo confined to optical disk

Position velocity plots: anomalous gas


Anomalous velocity gas

Chonis+ (2011)

Deep optical imaging: stellar streams and accretionfrom minor mergers


Chonis et al (2011) speculate the remnant of the 'a' loop stream could be located at the west end of the loop, just east of the 'c' feature.

Searching for anomalous velocity gas

700

600

500

400

300

Intensity Weighted Mean

Gaussian-Hermite


(vGH – vIWM) difference map700

600

500

400

300

Intensity Weighted MeanGaussian-Hermite

-

=

...highlights asymmetric profiles


(vGH – vIWM) difference map


(vGH – vIWM) difference map


mass estimate of cloud:~ 2 x108 M☉

Possible remnant? Or gas pulled from the disk during an interaction?

Complementary observations

APO Multi-longslit spectroscopy:Build up 2D optical spectra of HALOGAS edge-ons; compare ionized gas with HALOGAS HI observations

GALEXDeep NUV (+some FUV) observations:Detect outer disk star formation Detect UV emission reflected from

dust grains in halo

HALOSTARSDeep R-band imaging at INT:Search for stellar streams and counterparts to HI features

KPNO4-meter Mosaic 1.1:UBHaR imaging

Plus deep B imagingfor HALOSTARS complementary color information

Jozsa

Wu+, in prepPatterson

Adebahr+, in prep


Radio continuum

5 MHz of effective continuum bandwidth for first half of targets80 Mhz of full-polarization continuum bandwidth for second half

Deep optical imaging of NGC 925

Dwarf companion and stellar stream detected in B and R,corresponding to HI feature

HALOSTARSR band

KPNO (B= blue, R=green, Halpha=red)

dwarf location


PRELIMINARY

Companion:LR ~ 1.85 × 107 L⊙M∗,R ~ 3 × 106 M⊙

In short...the HALOGAS survey galaxies show a range of HI features:

HVC analogs, companions, thick disks, streams, and filaments.


Stay tuned for upcoming publications: http://www.astron.nl/halogas/http://www.astron.nl/halogas/

Appendix: Full sample


Appendix: SFR


Appendix: NGC 5055 model parameters


Appendix: Environmental properties


results from the halogas surveyresults from the halogas survey: hi observations of ngc 5055 maria...

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